The Design Of GPON OLT Receiver Circuit

With the development of Internet application, video application and high-definition television, larger bandwidth is needed. Nowadays, access technologies such as xDSL can not provide enough bandwidth to support high-bandwidth applications like video on demand, interactive games, or video conference. So Fiber To The Home(FTTH) is imperative. As the most potential fiber access technology, GPON is high-speed, high efficiency, and high reliability. Furthermore it is characteristic of provide multi-service transparent transmission. With the development of optical devices, the cost of GPON access network is reducing. So compared with other access technology, GPON has a brighter future.In this dissertation, the design plan of GPON OLT receiving circuit was proposed firstly on the base of analyzing and researching the GPON technology standards, then RTL coding, RTL simulation, and FPGA prototyper emulation is performed. Our design is proved to work well and realized all the functions included in the ITU-T G.984.3 (transmission convergence layer specification).The dissertation focuses on the RTL design of GPON OLT receiving circuit, including circuit structure, module partitioning and the detail design of each functional module, such as GTC synchronization, descrambling, alarm generating, clock field transforming, reed-solomon decoding(error correcting), CRC(Cyclic Redundancy Check), HEC(Header Error Control), GEM frame synchronization, payload reassembling, and queue attemperation.RTL simulation of GPON OLT receiving circuit was also introduced in this dissertation. Combined with the sending circuit of ONU, the FPGA prototype emulation was performed. The results show our design of OLT receiving circuit can realize the correlated functions of ITU-T G.984.3 standard, and achieve the anticipative demands .